Conventional winding structures of a rotating electric machine are for example disclosed in Japanese Patent Laying-Open Nos. 2000-217290 and 10-313557.
Japanese Patent Laying-Open No. 2000-217290 discloses an electric motor in which windings of each phase are connected in the manner that windings opposite to each other in the radial direction are connected in parallel and a set of thus parallel-connected windings is connected in series with another set of parallel-connected windings.
Japanese Patent Laying-Open No. 10-313557 discloses a rotating electric machine for which the number of turns of windings opposite to each other is adjusted so as to adjust unbalanced magnetic pull.
In some cases, a rotor and a stator of a rotating electric machine are disposed eccentrically with respect to each other, namely respective centers of the rotor and the stator do not coincide. Here, in a winding structure in which series-connected coils are connected in parallel with other series-connected coils, imbalance in electromotive force due to the eccentricity could generate cyclic current in the parallel circuit to accordingly cause increases of vibrations and noise of the rotating electric machine while it is driven.
However, as disclosed in Japanese Patent Laying-Open No. 2000-217290, in the case where parallel circuits are formed for each coil, the larger number of points of connection leads to deterioration in workability and increase in size.
As for the winding structure disclosed in Japanese Patent Laying-Open No. 2000-217290, the adjustment is made in the number of turns, not in the arrangement of windings.